oh spontaneous! why didn’t you say so. What about the guy?
Even though guys generally need MUCH less time to prepare
than the girl, still it depends on the sitch some guys might be annoyed at it, though as you said, suggesting is just that.
I’d say when your sure its going somewhere from both sides.
guy likes you, you like him, so will be happy to work w/ you.
but two hours notice? common! might be too little.
How would you feel getting 2 hrs notice?
Remember guy needs a shave, shower, has to find a place, maybe needs a reservation, driving in from work traffic etc. So be reasonable. Hatzlacha!
At least most mainstream yeshivisha guys need a shave.